In U.S. Pat. No. 3,836,685, R. E. Schara et al explain some of the problems associated with the fat released during the preparation of meat-in-gravy products, such as meatballs-in-gravy, meat chunks in a sauce, and the like, for either animal or human consumption. They state that such products are generally packaged in raw or partially cooked form and then cooked to their end point and sterilized by the application of heat to the sealed package using a process commonly referred to as retorting. In such a process, the fat, whether inherently contained in the meat portion or present as added fats, melts by virtue of the high temperatures to which it is subjected. As a result, the fat migrates from the meat pieces to the gravy portion of the product. Upon returning the packaged product to ambient conditions for distribution to the consumer, the melted fat returns to its solid form resulting in the formation of a "fat-cap" at the top of the package.
This fat-cap, besides being unsightly and, therefore, detrimental to consumer appeal, hinders the pourability of the contents of the can, and in some cases the products must be spooned out. Even if the packaged product is to be heated by the ultimate consumer, thereby liquifying the fat, the fat will be in the gravy portion of the product as opposed to the meat pieces, resulting in a gravy of thicker viscosity than originally formulated and also meat pieces lacking the characteristic mouthfeel imparted by the fat. To correct this problem, Schara et al add lipophilic fillers to a ground meat-containing formulation employed to make meat balls or chunks. They indicate that neither farinaceous fillers, such as wheat flour or cereal, nor proteinaceous fillers, such as finely ground caseinate, were satisfactory. However, the employment of nutritionally inert fillers adds cost, provides no nutrition, and takes the place of flavorful materials. Moreover, these inert fillers do not solve an equally serious problem of gravy gelation with products of this type.
In U.S. Pat. No. 3,843,815, S. A. Reesman states that it is well known that the connective tissue of the principal muscles of meat used in making the meat pieces in products of the type mentioned above contains the protein collagen. Collagen on heating in the presence of moisture dissolves and yields gelatin. Thus, subjecting a packaged meat-in-gravy product to high temperatures results in a "cooking-out" of the collagen and its decendent gelatin. When the packaged product is returned to room temperature for distribution and use, the gelatin, according to its well-known properties, causes the gravy to gel and results in a final product which is not readily pourable but must be spooned out.
Reesman discloses that the addition of from about 0.5 to about 3.5 percent of a weak acid will correct this problem. However, this adds expense and acid pH values or flavors associated with certain weak acid ions, are not suitable for many food products. Moreover, this technique does not solve the problem of fat-cap formation.
In U.S. Pat. No. 3,881,031, M. Glicksman et al propose another solution to the problem of cooking out of protein with resultant gravy gelation. They disclose that the addition of certain anionic polymers, such as sodium carrageenate, xanthan gum, gum tragacanth, sodium alginate, gum karaya, and the like, permits a retorted meat and gravy product to remain pourable after cooking. The addition of these materials, however, adds cost without solving the problem of fat cap formation.
In an earlier disclosure, in U.S. Pat. No. 3,574,633, R. J. Flier suggests that a canned meat and gravy product be cooled as rapidly as possible to minimize fatting out of the fat content of the disclosed meat chunks.
U.S. Pat. No. 3,898,345 to D. Horrocks et al is directed to preparing meat-like chunks from textured vegetable proteins, e.g., spun fibers, which are capable of canning with a gravy. They disclose forming fiber bundles and binding them into groups with a binding emulsion. The emulsion can contain flavorant such as liver, colors such as blood, fat, and other ingredients in addition to binders which can be of the heat settable type such as wheat gluten, blood plasma, egg albumen, starches and cellulose ethers, or other materials such as gelatine. They state that if the product is to be canned and sterilized in a static retort, the product can be made with sufficient integrity to withstand cutting, mixing with other materials, and canning. The materials which help to achieve this toughness by cementing the whole into a coherent mass, such as carrageenan jelly or fat, are said to be leached out of the product during sterilization, leaving a fragile chunk with the easy collapse properties of stewed steak. These products are, however, complex and costly to form and there is no indication that the problems of free fat or gravy gelation are alleviated.
In U.S. Pat. No. 4,247,562, J. W. Bernotavitz describes a method for preparing a canned food product composed of a nutritionally fortified liquid gravy and blood-based, retort-stable, meat-like chunks for use with dry pet foods or to use alone. The chunks are composed mainly of blood and employ a gum to stabilize the blood-based chunks. The gravy has added fat, flavorings and thickeners. The product is disclosed as being retort stable, however, without the presence of high meat levels or fat contents reasonable for palatability or nutrition in the meat pieces, the disclosure is inapposite to the problems associated with meat ball and meat chunk in gravy products.
Thus, there remains a present need for a canned meat and gravy pet food which is highly palatable due to high meat and significant fat contents, which has meaty pieces exhibiting high integrity and a gravy component which is flowable from the can and coats the meaty pieces to provide a high sheen with no significant fat in the gravy. Additionally, there is a need for a process for producing foods of this type on a commercial scale.